From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6F6934399F3; Fri, 24 Jul 2026 14:14:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784902489; cv=none; b=Mwgu9lq673leWfLVxiyNj16EraUiGUfoDilV7VNJXCf5pA5vRShyKPkweyaA4Jg8jY44ChtHrlwpHQuP3UMavX+wG66ya4Ll1iNwbzEp+1YfpWZYv3Mf+z/TWVLKIjI+Ojg7XZXeqBOGJGxbAjE+EaJgDYhDOJSO7u75tHQC7j8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784902489; c=relaxed/simple; bh=JCpz07QMIoYkgWlFbFkBXaMEQIeBpd6j7HAefVsL008=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ho6n9Qp1YuAoPQ2eMNTokk72U10T3XNjQwmPS5fO+xW3UnopcngphZLTUWvdNKiQ2E8GzyIJvCkiNQMXzL0p8VZPnzcX0NjBmalBUgynOdV2RYsPyhosN4eqTDsIadPH4WoIc0QaaTxyxzGccykxkytctoPQZcKapIBDxAzkHP8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=SHacB/p3; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="SHacB/p3" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784902485; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CtBv+6DKpRgeUFFG4TgzRtR+eRItYzi9T1OzkhCupJw=; b=SHacB/p335Ksp6x94cwKEounO35MYO6UNiaadteJdmJOK6XBUmunYbgvq4+bGzeEpwrNVB 7PCRRvldTxswTNOa3q/yVHZzGJtUvVMZHmb1mTKQlQBxz5DTsQd1KBmICwG8s4YKiqgJDO MOBCyETxKzHxS2a4pTie5MnPmZceY94= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan , Sechang Lim , Varun R Mallya , Leon Hwang , Viktor Malik , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH bpf-next 1/2] bpf: Fix sleepable check for tracing prog Date: Fri, 24 Jul 2026 22:14:21 +0800 Message-ID: <20260724141422.10463-2-leon.hwang@linux.dev> In-Reply-To: <20260724141422.10463-1-leon.hwang@linux.dev> References: <20260724141422.10463-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT When CONFIG_FUNCTION_ERROR_INJECTION is disabled, a sleepable tracing prog is allowed to attach to '__x64_'-alike prefix symbols. It is because the verifier does not verify whether the symbol is a kernel function or a bpf prog. That said, a sleepable tracing prog is allowed to attach to a bpf prog target whose name has '__x64_'-alike prefix. For example, a sleepable fentry prog attaches to a '__x64_sys_nop' XDP prog, and copies buffer from a user pointer with bpf_copy_from_user() helper. After attaching the XDP prog to lo interface, the kernel BUG could be triggered by 'ping -c 1 -W 1 127.0.0.1': [ 3.460756] BUG: sleeping function called from invalid context at kernel/bpf/trampoline.c:1324 Fix it by disallowing sleepable tracing prog always when its target is bpf prog. Fixes: 16d9c5660692 ("bpf: Always allow sleepable programs on syscalls") Signed-off-by: Leon Hwang --- kernel/bpf/verifier.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 52be0a118cce..40d567b90d24 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -18935,13 +18935,16 @@ static bool is_tracing_multi_id(const struct bpf_prog *prog, u32 btf_id) } static int btf_id_allow_sleepable(u32 btf_id, unsigned long addr, const struct bpf_prog *prog, - const struct btf *btf) + const struct btf *btf, const struct bpf_prog *tgt_prog) { const struct btf_type *t; const char *tname; switch (prog->type) { case BPF_PROG_TYPE_TRACING: + if (tgt_prog) + return prog->sleepable ? -EINVAL : 0; + t = btf_type_by_id(btf, btf_id); if (!t) return -EINVAL; @@ -19324,7 +19327,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, } if (prog->sleepable) { - ret = btf_id_allow_sleepable(btf_id, addr, prog, btf); + ret = btf_id_allow_sleepable(btf_id, addr, prog, btf, tgt_prog); if (ret) { module_put(mod); bpf_log(log, "%s is not sleepable\n", tname); @@ -19575,7 +19578,7 @@ int bpf_check_attach_btf_id_multi(struct btf *btf, struct bpf_prog *prog, u32 bt /* Check sleepable program attachment. */ if (prog->sleepable) { - err = btf_id_allow_sleepable(btf_id, addr, prog, btf); + err = btf_id_allow_sleepable(btf_id, addr, prog, btf, NULL); if (err) return err; } -- 2.55.0